By the time the Minelab PI's came out, nobody cared any longer about our greatest range of VLF's, most of us were too busy becoming SD mad to bother.
Except, I never let a good dog die. So I stayed in touch with my older units and bought new ones, to compare, use, and get them set up properly along side my SD's.
How good is the Eureka Gold on hot ground compared to other detectors? That question is quite often asked by those who have a true want for that knowledge, and they deserve a straight answer.
Utilising both tracking speeds, when well set up and with the right coils to match the frequency in use, and the right add-ons to make them sing ...They are deeper, more versatile, more sensitive and far easier to use on hot ground than some self styled experts would have anyone believe.
But I do not think that it is intentional, or misleading on purpose ....they simply do not know, as most have only heard one for a short time, either wrongly set up, or may even feel obliged to take a stab at repeating old wrongful opinions.
Across the entire range of Minelab gold VLF's, there has always been confusion over a proper threshold setting.
Some big gold hitters maintain the score running with no threshold at all, but, many signals are missed, that's fact. Successful or not.
The often quoted 'just audible' setting of a threshold was one of the main reasons people put VLF's down. Both in the user manuals, by dealers, users who had no idea but still put it into print. Culprits.
The proper threshold on hot ground is a nice and high full sound, stable and rock solid. Allowing the highest sensitivity they can muster. Causing lovely repeatable dropouts in the threshold on deep signals on heavy ground. Missed by a mile with that 'mosquito buzz setting', the worst throwaway line in detecting.
Here is a rundown on the Minelab VLF models, from before the inception of the Eureka platform, the start of that platform, and our soon to be discontinued leader of the VLF's.
It may be of slight help to those who own or are looking for a gold VLF that does a hell of a lot more than just tickle itself into girl-scout dirt.
Goldseekers 15000:
Minelab bought an Australian company that had manufactured two decent early VLF's, they then went on to produce the Goldseekers model in the early to mid 1980's.
Although the balance had more drift than the later models, they had the most proficient ground balance put on to a detector at that time.
They ate our old A2b's.
Balance was utilised by depressing and holding a handle button while adjusting the GB dial.
Around 8khz, very tough metal box, 8" round stock coil plus an 11" round.
These started the 5 pin coil connector range.
Eldorado MK1:
A low frequency unit, metal box, looking exactly like the Goldseekers only with green on the box in place of red. No disc, no nonsense, threshold based, and a very stable ground balance.
A most underrated unit. They cruised over hot ground a little better than the Goldseekers because they were slightly less sensitive, but held their balance and threshold level a little more stable.
They took the large coils well, and were on par with any later model Minelab gold VLF on big deep gold in hot ground.
Not very sensitive on the very small gold though.
You could size deep coins with this unit too, and the audio and pitch was so good on the machine that you could judge junk against coins by sound far better than any coin discriminating detector on the market at that time, and half of them today.
Eureka Ace Dual:
This was the one!
This green box machine will still out detect any current model Fisher, Whites, Tesoro or Garrett VLF units on truly mineralised ground today. Deep large, shallow and small. That's how good they were.
Carrying a twin frequency choice of 8khz and 20khz, they still have the most stable manual ground balance of any VLF ever produced. They were nice and sensitive but still handled heavy ground manually like a champ, a real pleasure to work with.
Mounted with a half rounded clip, they could be set up on a straight shaft, upside down on the top of the shaft directly in front of the hand grip, so the ground balance dial was in your right index fingers range. You could ride that ground balance to your hearts content.
Eldorado MK11:
Another plastic box unit.
Yellow in colour and running in 8khz. Made as the cheapest basic gold VLF just to fill the entry level stage.
Minelab's worst ever detector. All they had to do was make the ground balance solid and unwavering. Instead, we got the most drifting ground balance ever made, and I mean drifting! And an extremly broad response, that when combined with it's lack of sensitivity, made for a very sour unit. Completely useless for any type of detecting.
GT16000:
Here starts our Auto ground balance and Auto tracking, along with a microproccesor.
8" round stock coil. Later the 6" little sensitive round and 11".
Mounted on the pole with a half rounded clip on.
Brilliantly designed units and so far ahead of other manufacturers detectors that it simply left all other units, bar the manual balancing Minelab's, in shock.
Although the Auto was breakthrough, some of us preferred the Dual Ace later on as we had full control on running positive balance with them.
But a delight the GT still was.
FT16000:
The FT were similar to the GT, with a slightly faster tracking speed. Some did not like the faster balance, but I preffered it, as the proccessor seemed to function quicker than the GT, and big coils on hot ground seemed to suit it's pickup on ground changes, with a nicer sharpness to threshold dropouts .... and those were the main signal we were looking for.
Later the FT would be marketed to America as the Klondike.
Both the GT and FT had a discriminator on board. But only escaped mental patients would use the function.
Some very impressive large aftermarket coils were made to fit the entire 5 pin range, and then the4 pin series, thanks to men like Barrie Johnson, Bob Hollins and a few others.
They also started the spurn of aftermarket signal enhancers and modifications, because we finally had units worthy of mods, thanks to men like Ken Roberts and quite a few others that had cut their teeth modding early Whites and Garretts. They helped us to tame the hot ground with the 5 pin range of Minelab's.
XT17000:
Blue plastic box, the first to slide into a stem mounted clip. The second twin frequency unit, this time in 6.4khz and 32khz. Tone dial on the rear being adjustable with a flathead.
A nice tracking speed, lovely sensitivity, but you could do more with this unit by the tone dial, and it helped to run a more varying threshold.
The coil range starts to really open up from here on in, with the stock 8" round, 6" round, 10" elliptical, 11" round, 17"elliptical. Big round West Australian coils, the list never ended
Goldstriker:
Red plastic box, Similar to the XT17000. But only ran in 32khz and had the tone dial on the face plate. 10" elliptical stock coil.
They played with the signal responses on these models, running a boost, coarse and fine. They all seemed to behave a little differently that the boost, normal, enhance on the other models.
I felt they handled a bit too delicately than the 17000's in a few areas overall, and weren't nearly as good a unit.
XT18000: Version 1
This early model carried, for the first time, 3 frequencys. 6.4, 20 and 60khz. With the coil choices available on the 4pins, stock 10"x5" or round 8" depending when and where you bought it, the 11"round. The Coiltek 14.5 inch all terrain beauty was and still is, the best large coil for both the 5 and 4 pins ever produced.
This first version was by far the most sensitive to date, it had an immaculate ground tracking speed and smoother everything. Nice loud audio.
The 60 kHz was so good on these you could actually feel it tickling it's way into to first inch of ground.
Unfortunately they would blank out over surface targets or on heavy ironstone outcropping. But this was soon to be changed.
The tone dials have always been a bugbear. Those dials can cause added drift on the thresholds audio level. Slight, but annoying.
I always felt a solid fixed, but still changeable tone control, would have been a better option.
XT18000: Version 11
Minelab employed a fellow from overseas to work with them. He improved on the original unit, did incredible things with the internals and stopped this blanking out. This unit became the most stable of the platform to date, in every way. A threshold so stable it was physical.
This model would later have a major cosmetic and battery system change, along with a twin tracking speed, to became the Eureka Gold.
Golden Hawk:
They tried something different with this machine. Placing it on an supposedly ergonomic shaft, looking very much like a version of an mini SD. Mounting the SD looking box clipped under and onto the handgrip. A heavy battery hooked on via a lead in the same way the SD did, belt mounted. All dismantled and folded away in a two foot long zip up carry bag.
One lot of accessories, belt pouches, bag etc. came in kaiki, another type you could get came in camo.
The same 3 frequency's as the 18000, but with a double tracking speed, and a slow and fast recovery switch. Neither of which seemed to show any real difference in either setting.
These had a terrible audio. And came with a dull 8" stock coil. The accessory 15" black coil you could buy for them was probably the worst coil Minelab ever made, a really bad coil. An absolute stinker.
Most of the units above ran an enhanced, fine or boost signal setting. Apart from the good normal setting. All of those settings other than normal, were particularly bad to use. Enhance upset balance timings, fine was a horrible little sound, and boost would more often that not send the unit into spasms if a crow flew overhead.
Eureka Gold:
So long old mate. You were the greatest of your breed.
Something new and improved always comes along ....I just hope and trust it will serve the memory of your kind with distinction.
Except, I never let a good dog die. So I stayed in touch with my older units and bought new ones, to compare, use, and get them set up properly along side my SD's.
How good is the Eureka Gold on hot ground compared to other detectors? That question is quite often asked by those who have a true want for that knowledge, and they deserve a straight answer.
Utilising both tracking speeds, when well set up and with the right coils to match the frequency in use, and the right add-ons to make them sing ...They are deeper, more versatile, more sensitive and far easier to use on hot ground than some self styled experts would have anyone believe.
But I do not think that it is intentional, or misleading on purpose ....they simply do not know, as most have only heard one for a short time, either wrongly set up, or may even feel obliged to take a stab at repeating old wrongful opinions.
Across the entire range of Minelab gold VLF's, there has always been confusion over a proper threshold setting.
Some big gold hitters maintain the score running with no threshold at all, but, many signals are missed, that's fact. Successful or not.
The often quoted 'just audible' setting of a threshold was one of the main reasons people put VLF's down. Both in the user manuals, by dealers, users who had no idea but still put it into print. Culprits.
The proper threshold on hot ground is a nice and high full sound, stable and rock solid. Allowing the highest sensitivity they can muster. Causing lovely repeatable dropouts in the threshold on deep signals on heavy ground. Missed by a mile with that 'mosquito buzz setting', the worst throwaway line in detecting.
Here is a rundown on the Minelab VLF models, from before the inception of the Eureka platform, the start of that platform, and our soon to be discontinued leader of the VLF's.
It may be of slight help to those who own or are looking for a gold VLF that does a hell of a lot more than just tickle itself into girl-scout dirt.
Goldseekers 15000:
Minelab bought an Australian company that had manufactured two decent early VLF's, they then went on to produce the Goldseekers model in the early to mid 1980's.
Although the balance had more drift than the later models, they had the most proficient ground balance put on to a detector at that time.
They ate our old A2b's.
Balance was utilised by depressing and holding a handle button while adjusting the GB dial.
Around 8khz, very tough metal box, 8" round stock coil plus an 11" round.
These started the 5 pin coil connector range.
Eldorado MK1:
A low frequency unit, metal box, looking exactly like the Goldseekers only with green on the box in place of red. No disc, no nonsense, threshold based, and a very stable ground balance.
A most underrated unit. They cruised over hot ground a little better than the Goldseekers because they were slightly less sensitive, but held their balance and threshold level a little more stable.
They took the large coils well, and were on par with any later model Minelab gold VLF on big deep gold in hot ground.
Not very sensitive on the very small gold though.
You could size deep coins with this unit too, and the audio and pitch was so good on the machine that you could judge junk against coins by sound far better than any coin discriminating detector on the market at that time, and half of them today.
Eureka Ace Dual:
This was the one!
This green box machine will still out detect any current model Fisher, Whites, Tesoro or Garrett VLF units on truly mineralised ground today. Deep large, shallow and small. That's how good they were.
Carrying a twin frequency choice of 8khz and 20khz, they still have the most stable manual ground balance of any VLF ever produced. They were nice and sensitive but still handled heavy ground manually like a champ, a real pleasure to work with.
Mounted with a half rounded clip, they could be set up on a straight shaft, upside down on the top of the shaft directly in front of the hand grip, so the ground balance dial was in your right index fingers range. You could ride that ground balance to your hearts content.
Eldorado MK11:
Another plastic box unit.
Yellow in colour and running in 8khz. Made as the cheapest basic gold VLF just to fill the entry level stage.
Minelab's worst ever detector. All they had to do was make the ground balance solid and unwavering. Instead, we got the most drifting ground balance ever made, and I mean drifting! And an extremly broad response, that when combined with it's lack of sensitivity, made for a very sour unit. Completely useless for any type of detecting.
GT16000:
Here starts our Auto ground balance and Auto tracking, along with a microproccesor.
8" round stock coil. Later the 6" little sensitive round and 11".
Mounted on the pole with a half rounded clip on.
Brilliantly designed units and so far ahead of other manufacturers detectors that it simply left all other units, bar the manual balancing Minelab's, in shock.
Although the Auto was breakthrough, some of us preferred the Dual Ace later on as we had full control on running positive balance with them.
But a delight the GT still was.
FT16000:
The FT were similar to the GT, with a slightly faster tracking speed. Some did not like the faster balance, but I preffered it, as the proccessor seemed to function quicker than the GT, and big coils on hot ground seemed to suit it's pickup on ground changes, with a nicer sharpness to threshold dropouts .... and those were the main signal we were looking for.
Later the FT would be marketed to America as the Klondike.
Both the GT and FT had a discriminator on board. But only escaped mental patients would use the function.
Some very impressive large aftermarket coils were made to fit the entire 5 pin range, and then the4 pin series, thanks to men like Barrie Johnson, Bob Hollins and a few others.
They also started the spurn of aftermarket signal enhancers and modifications, because we finally had units worthy of mods, thanks to men like Ken Roberts and quite a few others that had cut their teeth modding early Whites and Garretts. They helped us to tame the hot ground with the 5 pin range of Minelab's.
XT17000:
Blue plastic box, the first to slide into a stem mounted clip. The second twin frequency unit, this time in 6.4khz and 32khz. Tone dial on the rear being adjustable with a flathead.
A nice tracking speed, lovely sensitivity, but you could do more with this unit by the tone dial, and it helped to run a more varying threshold.
The coil range starts to really open up from here on in, with the stock 8" round, 6" round, 10" elliptical, 11" round, 17"elliptical. Big round West Australian coils, the list never ended
Goldstriker:
Red plastic box, Similar to the XT17000. But only ran in 32khz and had the tone dial on the face plate. 10" elliptical stock coil.
They played with the signal responses on these models, running a boost, coarse and fine. They all seemed to behave a little differently that the boost, normal, enhance on the other models.
I felt they handled a bit too delicately than the 17000's in a few areas overall, and weren't nearly as good a unit.
XT18000: Version 1
This early model carried, for the first time, 3 frequencys. 6.4, 20 and 60khz. With the coil choices available on the 4pins, stock 10"x5" or round 8" depending when and where you bought it, the 11"round. The Coiltek 14.5 inch all terrain beauty was and still is, the best large coil for both the 5 and 4 pins ever produced.
This first version was by far the most sensitive to date, it had an immaculate ground tracking speed and smoother everything. Nice loud audio.
The 60 kHz was so good on these you could actually feel it tickling it's way into to first inch of ground.
Unfortunately they would blank out over surface targets or on heavy ironstone outcropping. But this was soon to be changed.
The tone dials have always been a bugbear. Those dials can cause added drift on the thresholds audio level. Slight, but annoying.
I always felt a solid fixed, but still changeable tone control, would have been a better option.
XT18000: Version 11
Minelab employed a fellow from overseas to work with them. He improved on the original unit, did incredible things with the internals and stopped this blanking out. This unit became the most stable of the platform to date, in every way. A threshold so stable it was physical.
This model would later have a major cosmetic and battery system change, along with a twin tracking speed, to became the Eureka Gold.
Golden Hawk:
They tried something different with this machine. Placing it on an supposedly ergonomic shaft, looking very much like a version of an mini SD. Mounting the SD looking box clipped under and onto the handgrip. A heavy battery hooked on via a lead in the same way the SD did, belt mounted. All dismantled and folded away in a two foot long zip up carry bag.
One lot of accessories, belt pouches, bag etc. came in kaiki, another type you could get came in camo.
The same 3 frequency's as the 18000, but with a double tracking speed, and a slow and fast recovery switch. Neither of which seemed to show any real difference in either setting.
These had a terrible audio. And came with a dull 8" stock coil. The accessory 15" black coil you could buy for them was probably the worst coil Minelab ever made, a really bad coil. An absolute stinker.
Most of the units above ran an enhanced, fine or boost signal setting. Apart from the good normal setting. All of those settings other than normal, were particularly bad to use. Enhance upset balance timings, fine was a horrible little sound, and boost would more often that not send the unit into spasms if a crow flew overhead.
Eureka Gold:
So long old mate. You were the greatest of your breed.
Something new and improved always comes along ....I just hope and trust it will serve the memory of your kind with distinction.
I still have a GM-11 I bought off a bloke who got it new , he tried it once & gave up , I took it out on hot ground & it howled ' screamed & cried , even tried it at Tibooburra on dead quiet ground where it could not be ground balanced ( they need some mineralisation ) just made moaning noises ! 
-John